Free API & Dev Tools Tools
6 API & Dev Tools listings are free or have a free plan: 1 free outright and 5 freemium, with paid upgrades. Pricing is maker-supplied and may be out of date.
Actionbox
Add human approvals to AI agents, scripts, and CI/CD workflows with the hosted ActionBox API, a reviewer inbox, and durable decisions.
Free plan (paid upgrades) · listed Saturday, 10 October 2026
GreenCalculus API
Sourced emission factors and audit-traced carbon calculations behind one API - every value returned with its exact source cell, pinned to the data version you…
Free plan (paid upgrades) · paid plans from $49 · listed Saturday, 19 September 2026
MarsX
AI-powered dev tool for building web and mobile apps out of micro-apps combining no-code and code interfaces.
Free plan (paid upgrades) · listed Tuesday, 8 September 2026
Shipvela
Website hosting from GitHub or your terminal
Free plan (paid upgrades) · paid plans from $29 · listed Thursday, 29 October 2026
SolarGridCheck
Free UK grid screen for landowners: nearest substation and published headroom for solar or battery storage
Free · listed Monday, 12 October 2026
SVG Release Pack + local checker
Check SVG integration issues locally, then get a fixed-price React asset pack.
Free plan (paid upgrades) · paid plans from $29 · listed Thursday, 15 October 2026
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